STUDIES ON SUSPENSION AND EMULSION .51. PECULIAR MORPHOLOGY OF COMPOSITE POLYMER PARTICLES PRODUCED BY SEEDED EMULSION POLYMERIZATION

Composite polymer emulsion particles which consist of two kinds of polymer are prepared by seeded emulsion polymerization. In general, there are few situations in which the two polymers are completely mixed. Therefore, during polymerization the phase separation of polymers occurs in the particles and polymer particles with different heterogeneous structures are formed at the end of the process according to the polymerization conditions. The authors are interested in this polymer mixing process in microparticles with diameters in the range 0. 1-1. 0 mu m (1-8) because the properties of films cast from such composite polymer emulsions were clearly varied corresponding to the morphology of particles, even if the polymer compositions are the same. In addition, in those polymerizations the authors also observed some anomalous particles, e. g. , 'confetti-like', 'raspberrylike', and 'void' particles. These problems are also discussed.